In electric vehicles or hybrid electric vehicles, it is important to reduce sizes and costs of parts to be provided. A power conversion apparatus for converting a direct current of a battery into an alternating current of a motor is no exception and reduction in size and costs thereof is demanded. As a result, a heat density becomes large, and therefore it is necessary to improve coolability.
Among electronic parts constituting the power conversion apparatus, an electronic part having the largest heating value is a power semiconductor module. In order to improve coolability of the power semiconductor module, a double-sided cooling structure (PTLs 1 to 3) in which grease having a large thermal resistance is not used and heat is radiated from both sides of a semiconductor element is effective.